Transparent Gearbox on a Homemade Bicycle




I wantedcreate afor a long timebikewithgear boxin thebottom bracket

as IExpandeda rimrearhuband built acustomcoaster,
Icould not havegear....andI missed it!

I'minspired by oldbikes(1900),andtractor mowergearbox!

I usedbikegears,plexiglassandmachinedparts

I puttwo weeksto get the ideaand createplans
andabout 2 months torealizethe gearbox!

there are threespeeds andaxisdriveand outputare the same
theselection systemis brass

plexiglassboxisto see themechanism

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1:

FirstI madeplans andgear ratio

Planswere madetothescaleto facilitatemanufacturing andvarioustestsof setting up

Step 2:

the systemconsists ofa shaft on whicha gear isdrivenall the timeand the twootherturn in theblank

whenyou changethespeedwhich wasledstartsto rotatein the airand it isanother thattakes over


for machininggearssupports, aspecial machine(mortiser) was used

I had todisassemblea lot ofspeedfreewheelbikein order to makethis arrangement

Ithenjust solderthe sprockets ontheir support

Step 3:

then, and stillbrass, Imachined"sliding"

it slideson the shaftand causes afinger, whichthanks toa spring,causesthe pinionthatis desired, while leavingthe others free

just asa system oftractormower!

Step 4:

ThenI set up atemporaryChassismechanismtotry...

- Bottom4sprocketsrotateat the same time
-Righttherethe output gear(the piecewith theredlinesallows to seetherotation)
-Top left, the threesprocketsrotateindependentlyof each other(thebrassShiftingused to lockthe one youwant)

here you can see in works

Step 5:

manufactureof the boxto receive themechanism

I askedafriendsto machine thebearinglocation

for the restI did everythingby hand,witha hole sawand ajig saw....not easy!

canperceivethe selectorandbearing housings

space that Ishows withmy fingersused to placethe gearboxon the bike

to assemblethe pieces ofplexiglass,I used aspecialglueplanned forthis

Step 6:

tediousbutimportant step, polishing!

I used severalgradesandpaper:

100, 240, 400,800, 1000, 2500 and 4000

thenpolishhasis sufficientvehicle body

Thisisthe same methodtorenovatetheplastic headlights;-)

someonetold meit looks

Step 7:

I was missing6 mmin order to closethe boxproperly ....
SoI usedorangeplexiglassto fill this gap

orange ...why?
because I loveorange
becauseaccording to the angleof view, reflectionsgives the impressionthat the entiregearboxis coloredsothatthere isveryfeworange

Step 8:

for theselector,I usedpieces ofbrassIbrazedsilver

a smallplexiglasscovercanmake a little moresealedall

here is general aspect

Step 9:

the spring of thecablenot beingeffective, I madeanother systembetter finishto tighten thecable

here is the new system

Step 10:

remains only tomount thegearboxon my bikehomemade

I dono moredetailsthan thatthe bikebecause for methe main subject isthe gearbox!
a bikecustomissimple to dofor someone whoused to doit

evenwhenI putsome pictures of thebikeas I havealso spenttime on it

on the picturesit isa friendwho drives thebike
on thevideois me

Instructables Design Competition

Participated in the
Instructables Design Competition



    • Make It Fly Challenge

      Make It Fly Challenge
    • Stone Concrete and Cement Contest

      Stone Concrete and Cement Contest
    • Indoor Lighting Contest

      Indoor Lighting Contest

    58 Discussions


    7 months ago

    Incredible project !

    I didn't see how many gears do you have there. Same a a regular bike gearbox ?


    2 years ago

    cool project, and not to troll you or anything, but it is little hard to read your text when you don't use space in sentences.

    vijay mohans

    3 years ago

    great work. how much you did gain after this gear box, could you please explain and can you please post your work with 3D animation or diagram so it would be bit easy to make it. thanks


    6 years ago on Introduction

    you are an ENGINEER . this is the only word i can say now


    6 years ago on Introduction

    Beautiful work! Congratulations.
    This brings me some ideas to build a quadcycle :D.


    6 years ago on Introduction

    First congratulations for beautiful work.

    You told that “I put two weeks to get the idea and create plans and about 2 months to realize the gearbox!”

    I want to Design my own gearbox. So can you tell me which books help you to get the idea or information to make or design your gearbox?

    Please please please help me!

    4 replies

    Reply 6 years ago on Introduction

    I searched a lot on the internet but I have not found much information ....

    I wants to make available the most interesting of my research:

    system speed of tractor mower (pic 3)
    bikes with the old gearbox in the bottom bracket, (pic 6-8-9)
    a gearbox-chain (pic 5)
    one shema gearbox compact bike that I colored (pic 4)
    other system (pic 1-2)
    mine is a mixture of all that

    on the schema of the photo No. 7 there is a simple freewheel system
    it did not suit me at first because speed we can not pedaling backwards .... therefore the coaster brake that was not possible!

    otherwise it is a simple system realize!

    4904661856_9cdf0a020a_o.jpg612px-L-gear1.pngtransmission_for_lawn_mower.jpgpedalier couleurs.jpghoffmann-gearbox-003.jpgH1118-L13425964.jpgbv11.jpg128502987.oN1ekV0j.expovvwol12.jpgmagna debon.jpg

    Reply 6 years ago on Introduction

    How do you calculate gear ratio, number of teeth in pinion, speed and torque etc?

    And if I want to design my own gearbox what information do I need?


    Reply 6 years ago on Introduction

    for calculating gear ratios, it is not easy to explain with a translator ....

    for example, a standart Crankset about 45 teeth
    the sprocket wheel is about 15

    I used the principle of:

    A = 20 teeth on B = 10 teeth
    axis speed equivalent, B will turn two times faster than A

    after I did a lot of multiplication and division

    the rest has to give you ideas, observe plenty of mechanism and keep only what can be used on your gearbox


    Reply 6 years ago on Introduction

    You told me that "it is not easy to explain with a translator .... "

    So can you give me formulas that you use to make your gear box?


    6 years ago on Step 4

    You can have a setting that simply connects the pedals to the output.

    That would yield 4 ratios with no more chain or sprockets. simply make engagement from the brass selector ring to the output.

    Nice project.

    Blue Hawaii

    6 years ago on Introduction

    Wow! Really nice work! Very clean design. Your final project looks like a lot of fun to ride.

    I have used the following page to find many calculators when designing my projects.


    6 years ago on Introduction

    Two great concepts, the Gearbox, and the Bike, and went to my Blog.


    6 years ago on Introduction

    I believe with his shown skills he might be able to make a Nuvinci style gearbox for coaster system, after all it was invented by Leonardo Da Vinci so there should be no patent infringment, and if he did not seek to market it there should not be any conflicts at all.


    6 years ago on Introduction

    Holy Balls, that's amazing. Do you do this professionally as a bike builder?

    In regards to your comment of needing gearing for a wide rear wheel, they have Internally geared rear hubs. They are expensive, but let you have an 4-speed or 8-speed with only a single rear sprocket.

    Nuvinci: (these are crazy expensive, but rather "cool")
    Shimano: ("cheaper", but still much more expensive than regular sprockets)